In Macbeth, how should I compare and contrast Lady Macbeth's two soliloquies in Act 1?

Actually, in Act I, scene v, Lady Macbeth does have two
soliloquies, broken up by the entrance and exit of a Messenger.  The first one (lines
1-30) includes the reading of a letter from Macbeth.  The second (lines 39 - 55) ends
with Macbeth's entrance into the scene.

The first soliloquy
is important because, in this soliloquy she is cluing the audience in to her take on
Macbeth, and what she considers to be his weakness --

readability="9">

...I fear thy
nature,

It is too full o'the milk of human
kindness.

That wouldst thou holily; woulst not play
false...

...that which...thou dost fear to
do.

She seems, in this
soliloquy, a somewhat ambitious but very female wife.  She can only help to influence
Macbeth by "pour[ing her] spirits in [his] ear," and cannot effect the act
itself.

However, once the Messenger brings the news that
Duncan will be at the Macbeth's castle that night, she goes into action.  Gone is any
seeming hesitation about her role and she calls upon supernatural forces to aid
her:

...Come
you spirits

That tend on mortal thoughts, unsex me
here

And fill me from the crown to the toe
top-full

Of direst cruelty....Come thick
night,

And pall thee in the dunnest smoke of
hell,

That my keen knife see not the wound it
makes.

By this soliloquy, she
suggests to the audience that she will take matters in to her own hands, her own knife
shall be the one that strikes the evil blow that makes Macbeth
king.